Speedometer.



A. A. CANTON. SPEEDOMETER.

APPLICATION man mAYn.

Patefit May 8,1917.

Wigwam 15, 15 in a well known manner.

ALLEN A. CANTON, 035 NE)? 503K, 1?. L, ASSIQiIifUR T111", TE SiTIIIG GGIIPAE'Y,

A CORPORATIQN OF GQNNEQTIC'UT.

SPEEDOMETEPJ.

Specification of Letters Patent.

.n, 1r Q mac .11. men May 1, Ilsa i.

Application filed May 1?, 1913. Serial Ho. 768,220.

To all whom it may concern:

Be it known that I, ALLEN A. CANTON, citizen of the United States ofAmerica, and a resident of the city, county, and State of New York, haveinvented certain new.

and useful Improvements in Speedometers, of which the following is aspecification.

This invention relates .to speedometers. The object of the invention toprovide an electrically operated s"eeglometer of novel and usefulconstruction adapted .to be manufactured at a relatively low cost andone which may be easily attached to the vehicle the speed of which is tobe measured. Other objects ancillary to the main object of the inventionwill appear as this specification proceeds. v In the drawingaccompanying this specification and illustrating the invention Figure 1is a diagranmiatic View of an apparatus embodying the invention.

Fig. 2 is a detail view showing one form of interrupter or make andbreak device, and Fig. 3 is a diagrammatic view similar to Fig. l butshowing a modification.

Referring to Fig. 1 the numeral 5 desig nates an electromagnet havingthe coil 6 in the circuit 7-8 which includes the battery 9, a snapswitch 10 and the interrupter 11. 12 represents any suitable form ofelectrically operated counting device connected in series with theinterrupter. 13 represents a movable coil wound upon the soft iron core14 which is pivoted in bearings The shaft 16 of the core ll carries twocollector rings 17 to which the terminals of the coil 13 are connectedand which in turn are connected across the battery by the wires 18 and19 by suitable sliding terminals of the shunt wires 18 and it). 20 is aneedle secured to the shaft 16 and which moves over a suitable scale 21.The spring device 22 tends to keep the needle at zero in a well knownmanner.

The interrupter is suitably driven from the vehicle, the speed o1 whichis to be measured, and is so arranged that the frequency of theinterruptions in the circuit.

coil 13 which, because of well known prin ciples of electricity, causesa deflection or movement of the coil and. the shaft 16 which is observedin the movement of. the needle over the scale. The latter being suitablygraduated, the speed of the vehicle, trans lated through theinterrupter, may be read directly on the scale.

It will, however, be apparent, that the period of d ration of contact inthe interrupter, must be constant irrespective of the speed of thevehicle in order that the pulsations through the circuit '.?8 may be ofequal strength and cause a strengthening, directly proportioned in ratioto the frequency of interruptions, of the electromagnet so as to cause amovement of the needle large enough to be observed so as to be ofpractical value.

It the interrupter was in the form of an ordinary commutator drivendirectly at the vehicle speed, it is obvious that the faster thecommutator rotated. the shorter would be the period of duration ofcontact and the shorter would be the impulses in the circuit and themeasure of the speed expressed by the movement of the needle would besubject to two variable factors, namely, the speed and the length of theperiod of duration of contact in the interrupter, hence would beimpracticable as a speed indicator.

1 have overcome this difficulty by arranging the interrupter so that theperiod of duration of contact is constant irrespective of the speed ofthe vehicle, consequently the movement of the needle is subjected toonly one variable factor, namely, the speed of the vehicle, which thuscan be measured by the deflection of the coil 13 as seen by the positionof the needle with relation to the scale.

The arrangement is shown in Fig. 2 in which 25 represents the axle of afront automobile wheel 26. Upon this axle is mounted a gear 27 whichdrives another gear 287011 ashat't 29 carrying an arm or projection 30.31 represents a bracket or other support which secured to the vehicleand which supports the various parts as shown. The interrupter lfl ismounted on a shaft 32 and carries a ratchet 33. 34: a pawl pivot-allycarried by a reciprocating slide 35 in the bracket 31 having a dependinglug- 36 kept in contact with. the 30 by the spring 37.

The one wire 7 is connected to the shaft 32 hence to the conductingsegments 38 of the interrupter. The other wire 8 has a sliding terminal39 in contact with the circumfer ence of the interrupter like a brush.

The operation is as follows. The arm 30 on shaft 29 is rotated at thesame speed as the wheel axle and thus for each revolution the slide isforced to the left by the arm 30 striking the depending lug 36. As soonas the arm 30 has passed the lug 36 the slide 35 is pulled to the rightby the spring 37 and .this movement of the slide is of course constantno matter how often it occurs in a given time unit. The movement to theright causes the pawl 34: to engage and move the ratchet one tooth,consequently rotates the interrupter one step, so that it will beapparent that the period of duration of contact between any one segment38 and the wire terminal 39 is constant, because it depends upon thepull of the spring which is constant and not upon the speed of theshafts 2%) and 25,

from which it will be seen that the impulses o1- pulsations in thecircuit 78 are of an equal duration and that the strength of theelectro-magnet is varied in direct proportion with the frequency of theinterruptions, that is the speed of the vehicle.

In Fig. 3 I have shown an apparatus in which 40 represents a permanentmagnet and the strength of the current in coil 13 is varied directly bythe frequency of the interruptions in circuit 78.

The speedometer as here described may be started or stopped by theswitch 10, which of course might be automatic in its operation by themotion of the vehicle.

Details of construction may be varied within the principle of theinvention and the scope of the appended claims.

1. A speedometer comprising a movable indicator, an'electromagnet forproducing a magnetic field, a coil mounted to move with- .in saidmagnetic field to operate said movable indicator, an electric circuitfor supplying current to said elcctromagnet, a current interruptingdevice in said circuit and means for operating said interrupting deviceto cause current impulses of equal duration to pass through saidelectriccircuit and sai electromagnet.

2. A speedometer comprising a movable indicator, an electromagnet forproducing a magnetic field, a coil mounted to move within said magneticfield to operate said movable indicator, an electric circuit forsupplying current to said electromagnet, a current interrupting devicein said circuit and means for operating said interruptingdevice to causecurrent impulses of equal duration to pass through said electric circuitand said electromagnet irrespective of the ope 'ating speed of saidinterrupting device.

3. A-speedometer comprising a movable indicator, an electronnignet forproducing a magnetic field, a coil mounted to move within said magneticfield to operate said movable indicator, an electric circuit forsupplying current .to said electromagnet, a rotatable currentinterrupting device in said circuit and means for rotating said devicestepwise through a constant angle for each step irrespective of theoperating speed of said interrupting device.

-l. The combination with a shaft the speed of which is to be measured,of a speedometer comprising an indicator, an electric circuit. anelectromagnet therein for operating said indicator, means for varyingthe strength of said elcctromagnct com )rising a current interruptingdevice and a member driven by said shaft for intermittently operatingsaid device to cause current impulses of equal duration to pass throughthe said electric circuit and electronmgnct irrespective of theoperating speed of the said shaft.

5. The combination with a shaft the/speed of which is to be measured, aspecdmnctcr comprising an indicator, an elcctromagnct for operating saidindicator, means for passing current impulses of equal duration throughsaid .electromagnet to vary the strength thereof, said means comprisingan electric circuit an interrupting device for interrupting the currentin said circuit and means driven by 'said shaft for intermittentlyoperating said interrupting device.

Signed at New York, N. Y., this 1.6 day of May 1913.

ALLEN A. CANTON.

WVitnesses K. Ur. Ln Am), IVAN Komoslsnue.

